====================================================== WARNING: possible circular locking dependency detected 6.1.18-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor340/3630 is trying to acquire lock: ffffffff8cdc47b0 (cpu_hotplug_lock){++++}-{0:0}, at: static_key_slow_inc+0xe/0x20 kernel/jump_label.c:158 but task is already holding lock: ffffffff8cf5a688 (freezer_mutex){+.+.}-{3:3}, at: freezer_change_state kernel/cgroup/legacy_freezer.c:387 [inline] ffffffff8cf5a688 (freezer_mutex){+.+.}-{3:3}, at: freezer_write+0x9f/0x3e0 kernel/cgroup/legacy_freezer.c:426 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (freezer_mutex){+.+.}-{3:3}: lock_acquire+0x23a/0x630 kernel/locking/lockdep.c:5669 __mutex_lock_common+0x1d4/0x2520 kernel/locking/mutex.c:603 __mutex_lock kernel/locking/mutex.c:747 [inline] mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:799 freezer_attach+0xa8/0x280 kernel/cgroup/legacy_freezer.c:163 cgroup_migrate_execute+0x7e3/0x1060 kernel/cgroup/cgroup.c:2615 cgroup_attach_task+0x5a3/0x9a0 kernel/cgroup/cgroup.c:2906 __cgroup1_procs_write+0x2ee/0x460 kernel/cgroup/cgroup-v1.c:523 cgroup_file_write+0x2c6/0x690 kernel/cgroup/cgroup.c:4057 kernfs_fop_write_iter+0x3a2/0x4f0 fs/kernfs/file.c:330 call_write_iter include/linux/fs.h:2205 [inline] new_sync_write fs/read_write.c:491 [inline] vfs_write+0x7ae/0xba0 fs/read_write.c:584 ksys_write+0x19c/0x2c0 fs/read_write.c:637 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd -> #1 (cgroup_threadgroup_rwsem){++++}-{0:0}: lock_acquire+0x23a/0x630 kernel/locking/lockdep.c:5669 percpu_down_write+0x50/0x2e0 kernel/locking/percpu-rwsem.c:227 cgroup_attach_lock kernel/cgroup/cgroup.c:2431 [inline] cgroup_procs_write_start+0x1b0/0x630 kernel/cgroup/cgroup.c:2935 __cgroup_procs_write+0xf6/0x4a0 kernel/cgroup/cgroup.c:5135 cgroup_procs_write+0x25/0x50 kernel/cgroup/cgroup.c:5171 cgroup_file_write+0x2c6/0x690 kernel/cgroup/cgroup.c:4057 kernfs_fop_write_iter+0x3a2/0x4f0 fs/kernfs/file.c:330 call_write_iter include/linux/fs.h:2205 [inline] new_sync_write fs/read_write.c:491 [inline] vfs_write+0x7ae/0xba0 fs/read_write.c:584 ksys_write+0x19c/0x2c0 fs/read_write.c:637 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd -> #0 (cpu_hotplug_lock){++++}-{0:0}: check_prev_add kernel/locking/lockdep.c:3098 [inline] check_prevs_add kernel/locking/lockdep.c:3217 [inline] validate_chain+0x1667/0x58e0 kernel/locking/lockdep.c:3832 __lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5056 lock_acquire+0x23a/0x630 kernel/locking/lockdep.c:5669 percpu_down_read include/linux/percpu-rwsem.h:51 [inline] cpus_read_lock+0x3e/0x150 kernel/cpu.c:310 static_key_slow_inc+0xe/0x20 kernel/jump_label.c:158 freezer_apply_state+0x1a6/0x3f0 kernel/cgroup/legacy_freezer.c:353 freezer_write+0x25e/0x3e0 kernel/cgroup/legacy_freezer.c:426 cgroup_file_write+0x2c6/0x690 kernel/cgroup/cgroup.c:4057 kernfs_fop_write_iter+0x3a2/0x4f0 fs/kernfs/file.c:330 call_write_iter include/linux/fs.h:2205 [inline] new_sync_write fs/read_write.c:491 [inline] vfs_write+0x7ae/0xba0 fs/read_write.c:584 ksys_write+0x19c/0x2c0 fs/read_write.c:637 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd other info that might help us debug this: Chain exists of: cpu_hotplug_lock --> cgroup_threadgroup_rwsem --> freezer_mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(freezer_mutex); lock(cgroup_threadgroup_rwsem); lock(freezer_mutex); lock(cpu_hotplug_lock); *** DEADLOCK *** 4 locks held by syz-executor340/3630: #0: ffff888079f02460 (sb_writers#10){.+.+}-{0:0}, at: vfs_write+0x269/0xba0 fs/read_write.c:580 #1: ffff888026ca8088 (&of->mutex){+.+.}-{3:3}, at: kernfs_fop_write_iter+0x1e7/0x4f0 fs/kernfs/file.c:321 #2: ffff8881457c20f0 (kn->active#56){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x20b/0x4f0 fs/kernfs/file.c:322 #3: ffffffff8cf5a688 (freezer_mutex){+.+.}-{3:3}, at: freezer_change_state kernel/cgroup/legacy_freezer.c:387 [inline] #3: ffffffff8cf5a688 (freezer_mutex){+.+.}-{3:3}, at: freezer_write+0x9f/0x3e0 kernel/cgroup/legacy_freezer.c:426 stack backtrace: CPU: 1 PID: 3630 Comm: syz-executor340 Not tainted 6.1.18-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106 check_noncircular+0x2fa/0x3b0 kernel/locking/lockdep.c:2178 check_prev_add kernel/locking/lockdep.c:3098 [inline] check_prevs_add kernel/locking/lockdep.c:3217 [inline] validate_chain+0x1667/0x58e0 kernel/locking/lockdep.c:3832 __lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5056 lock_acquire+0x23a/0x630 kernel/locking/lockdep.c:5669 percpu_down_read include/linux/percpu-rwsem.h:51 [inline] cpus_read_lock+0x3e/0x150 kernel/cpu.c:310 static_key_slow_inc+0xe/0x20 kernel/jump_label.c:158 freezer_apply_state+0x1a6/0x3f0 kernel/cgroup/legacy_freezer.c:353 freezer_write+0x25e/0x3e0 kernel/cgroup/legacy_freezer.c:426 cgroup_file_write+0x2c6/0x690 kernel/cgroup/cgroup.c:4057 kernfs_fop_write_iter+0x3a2/0x4f0 fs/kernfs/file.c:330 call_write_iter include/linux/fs.h:2205 [inline] new_sync_write fs/read_write.c:491 [inline] vfs_write+0x7ae/0xba0 fs/read_write.c:584 ksys_write+0x19c/0x2c0 fs/read_write.c:637 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7faf3decbde9 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 51 15 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fff9e1061e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007faf3decbde9 RDX: 0000000000000007 RSI: 0000000020000040 RDI: 0000000000000004 RBP: 0000000000000000 R08: 00007fff9e106210 R09: 00007fff9e106210 R10: 00007fff9e106210 R11: 0000000000000246 R12: 00007fff9e10620c R13: 00007fff9e106220 R14: 00007fff9e106260 R15: 0000000000000000